Specimen tilting device for particle beam apparatus



May 13, 1969 A. ASMUS 3,444,367 SPECIMEN TILTING DEVICE FOR PARTICLEBEAM APPARATUS FiledJune 29, 1965 Sheet of 4 Fig. 1

May 13, MU 3,444,367

SPECIMEN TILTING DEVICE FOR PARTICLE BEAM APPARATUS Filed June 29. 1965Sheet 3 of 4 May 13, 1969 A. ASMUS 3,444,367

SPECIMEN TILTING DEVICE FOR PARTICLE BEAM APPARATUS Filed June 29. 1965Sheet 3 of 4 A. ASMUS 3,444,367

SPECIMEN TILTING DEVICE FOR PARTICLE BEAM APPARATUS May 13, 1969 Sheet 4of4 Filed June 29, 1965 Fig. 6

United States Patent SPECIMEN TILTING DEVICE FOR PARTICLE BEAM APPARATUSAlexander Asmus, Berlin, Germany, assignor to SiemensAktiengesellschaft, Munich, Germany, a corporation of Germany Filed June29, 1965, Ser. No. 468,080

Claims priority, application Germany, June 30, 1964,

Int. Cl. H01j 37/26 US. Cl. 250-495 20 Claims ABSTRACT OF THE DISCLOSUREA specimen tilting device for a corpuscular ray apparatus, such as anelectron microscope. The device includes a tiltable specimen carrier andan adjusting plate which is spaced from this carrier. A support meanssupports the adjusting plate for tilting movement about a tilt axiswhich is adjacent to the adjusting plate and which extendsperpendicularly with respect to the principal or ray axis of the device.A means is provided for tilting the adjusting plate about this tiltaxis, and a transmission means which moves parallel to the principalaxis extends between and is in mechanical engagement with the adjustingplate and the specimen carrier for transmitting tilting of the adjustingplate to the specimen carrier. Because this transmission means -movesparallel to the principal axis, none of the components of the device arerequired to swing laterally about a tilt axis, so that only anexceedingly small space is required for the structure while at the sametime making relatively large tilting of the specimen carrier possible.

My invention relates to a tiltable device for accommodating a specimenwhich is to be studied or processed in a particle beam or corpuscularray apparatus, such as an electron microscope. As a rule, the specimenis supported on an apertured carrier, for example a diaphragm or asuitable mesh.

When using tilting devices of the above type, considerable difficultyhas been encountered on account of the fact that the device is situatedin an extremely restricted location where hardly any space is availablelaterally of the device to permit more than a very limited angular rangeof tilting movement for the specimen carrier. It is particularlydifficult to extend the tilt-adjusting structure from the outside to thelateral side of the tilting device, since with the known tilting devicesit is essential that the tilt control structure extend to the immediatevicinity of the specimen carrier, and this carrier, as a rule, islocated in a particularly inaccessible part of the apparatns, namelywithin the objective lens aperture.

It is therefore a primary object of my invention to avoid or minimizethe above-mentioned drawbacks by providing a structure capable oftilting the specimen carrier to any desired angle without any particulardifficulty both with respect to operation of the device andaccommodation of the latter in the particle beam apparatus.

In particular, it is an object of the invention to provide a specimentilting device which is of a relatively simple design but adapted to theparticular restrictions with respect to space usually encountered inparticle beam apparatus, such as electron microscopes.

A further object of the invention is to provide a tilting assembly ofthe above type wherein it is possible to place the tilt-angle controlstructure at a location where the difiiculties resulting from thestructure surrounding the specimen carrier itself are not present.

Thus, it is an object of the present invention to provide a tiltingdevice capable of determining the angular 3,444,367 Patented May 13,1969 position of the specimen carrier even if the latter, for example,is seated deep within the bore of a lens pole piece where no, or hardlyany, space is available at the side of the carrier for accommodatingsuch tilt control structure.

The objects of the invention further include devising a tilting devicecapable of providing a large range of angular movement for the specimencarrier without requiring a particularly large structure for producingthis result.

Another object of the invention is the provision of a structure capableof adjusting the angle of tilt of the specimen carrier even though thecarrier is introduced into the device along the principal axis of theparticle beam.

It is also an object of the invention to provide a structure which iscapable of tilting the specimen carrier not only about a single tiltaxis normal to the principal beam axis but also to any other desiredangular attitude.

It is furthermore an object of the invention to provide a structurewhich is capable of adjusting the angular attitude of the specimencarrier without creating any particular difficulties with respect tomaintenance of an evacuated interior within the particle beam apparatus.

In particular, the objects of the present invention include theprovision of a tilting structure which at least partly forms a unit witha cartridge which is removed from and replaced back into the rayapparatus in connection with changing the specimen so that, by making atleast part of the tilting structure unitary with this cartridge and thespecimen carrier, difficulties encountered with respect to maintenanceof a suitable vacuum in the interior of the device can be avoided.

The objects of the present invention also include the provision of astructure capable of providing an apparent angular orientation of thespecimen about the principal axis, which is to say an orientation inazimuth, without, however, actually turning the specimen itself.

Inasmuch as the specimen cartridge is conventionally mounted on a tablecapable of being shifted in a plane normal to the principal axis, theobjects of the present invention also include the provision of astructure capable of maintaining the angular attitude of the specimencarrier even while the specimen stage is shifted in its plane which isnormal to the principal axis.

The invention is illustrated by way of example in the accompanyingdrawings which form part of the application and in which:

FIG. 1 is a partly schematic sectional elevation of one embodiment of astructure according to the present invention;

FIG. 2 is a top plan view of the structure of FIG. 1;

FIG. 3 is a partly schematic sectional elevation of another embodimentof a structure according to the presene invention;

FIG. 4 is a top plan view of the structure of FIG. 3;

FIG. 5 shows an electron microscope partly in section, so as toillustrate the environment for the structure of FIGS. I4; and

FIG. 6 illustrates the manner in which specimen table of the electronmicroscope can be adjusted in a plane normal to the principal axis.

While the embodiment shown in FIGS. 1 and 2 provides a solution wherethe adjusting plate, specimen carrier, transmission therebetween, andspecimen cartridge all are assembled into a single unit, FIGS. 3 and 4show an embodiment where the adjusting plate and its support means aresituated beyond a unit which is formed in this case by the cartridge,specimen carrier, and transmission for transmitting movement of anadjusting plate to the carrier, as will be apparent from the descriptionwhich follows.

Assuming that the specimen to be studied or processed is mounted on adiaphragm disc 1 (FIG. 1-4) which is formed with a suitable aperturethrough which the principal axis 5 extends, a transmission means whichincludes elongated transmission members 2 is connected to, andcooperates with, the carrier 1 for moving parallel to the principal axisand tilting the carrier in response to tilting of an adjustable tiltingplate 8. As is apparent from the plan views of FIGS. 2 and 4, there arein fact three elongated motion-transmitting members 2 in the form ofrods spaced from each other 120 about the principal axis 5, this beingthe axis of the particle beam. The rods 2 are guided for movement by thecartridge 4 in a manner described below. The diaphragm 1, which formsthe specimen carrier, is mounted in a ring 10. As is shown most clearlyat the lower left portion of FIGS. 1 and 3, the ring 10 is formed at itsexterior with recesses having substantially the configuration of ahemisphere, and these recesses respectively receive the convexly curvedfree ends of projections extending laterally from the rods 2, so that inthis way a structure similar to a ball-and-socket joint is providedbetween the ring 10 of the carrier 1 and the longitudinally movable rods2. Therefore, when these rods 2 alter their longitudinal positionsrelative to each other the ring 10 and the carrier 1 therewith willnecessarily assume different angular attitudes.

In both of the embodiments disclosed in FIGS. 1-4 the rods 2 of thetransmission means are guided for longitudinal movement in bores 3formed in the cartridge 4 and extending therethrough in directionsparallel to the principal axis 5. The rods 2 respectively pass throughthe bores 3 in the manner shown in FIGS. 1 and 3. As is apparent fromFIGS. 1 and 3, the bottom ends of the bores 3 are of a smaller diameterthan the remainder thereof so as to provide for a sliding engagementwith the rods 2 at the place where they pass through the lowermostportions of the bores 3. Above these lowermost portions the bores 3accommodate springs 6 which are coiled about the respective rods 2 andengage collars fixed to the rods 2 and slidable in the portions of thebores 3 which are of a larger diameter. In this way the rods 2 are notonly guided for longitudinal movement but are also urged upwardly by thesprings 6.

In FIGS. 1 and 3 there is illustrated the adjusting plate 8 which isformed with a central aperture through which the principal axis 5extends. The plate 8 has a smooth undersurface 7 engaged by the convexlycurved top ends of the rods 2. Inasmuch as these smoothly and convexlycurved top ends of the rods 2 are maintained by the springs 6 inengagement with the surface 7, it is possible for the top ends of therods 2 and the surface 7 to have an easy sliding movement relative toeach other during tilting of the adjusting plate 8. This adjusting plate8 is tiltable in both embodiments about a tilt axis 9 which is normal tothe principal axis 5 and extends through the adjusting plate 8. It willbe seen that through the rods 2 of the transmission means any angle towhich the plate 8 is tilted about the tilt axis 9 will be transmitted tothe specimen carrier 1 so as to place the latter automatically in thesame angular attitude as the plate 8.

In the embodiment of FIGS. 1 and 2 the adjusting plate 8 is not directlymounted on the cartridge 4 for tilting movement about the tilt axis 9.Hnstead a gimbal 11 is situated between the plate 8 and the cartridge 4.The gimbal 11 surrounds the plate 8 and is formed with opposed bearingsthrough which the axis 9 extends. The bearings are engaged by respectivepins projecting from the plate 8 so that in this way the plate 8 issupported for tilting movement about the tilting axis 9 on gimbal 11.The gimbal 11 itself has a pair of coaxial pins 12 and 13 extendingalong a second tilt axis which is normal to the tilt axis 9 as well asto the principal axis 5, and these pins 12 and 13 are received insuitable bearings formed by openings of the cartridge 4 itself, so thatthe gimbal 11 is tiltable about an axis perpendicular to the tilt axis9. In this way a universal tilting movement of the plate 8 is possible,inasmuch as the plate 8 can tilt not only about the axis 9, but inaddition the entire axis 9 together with the plate 8 can tilt about thecommon axis of the pins 12 and 13. In this way virtually any angularattitude of the plate 8, and thus of the specimen carrier 1, can beachieved.

An adjusting means is provided for adjusting the angular attitude of theadjusting plate 8, and this adjusting means includes a pairof elongatedadjusting members 14 and 15 in the form of bars which have innerinclined wedge surfaces 14' and 15 in slidable engagement withrespective projections 16 and 17 of plate 8 and gimbal 11. Therefore,longitudinal movement of the adjusting bar 14 will adjust the angle ofthe plate 8 about the tilt axis 9 while longitudinal movement of theadjusting bar 15 will adjust the angle of the gimbal 11 about the commonaxis of the pins 12 and 13. This universal support for the plate 8affords setting the specimen at any desired angular attitude. The springmeans 6, maintaining the upper ends of the rods 2 in engagement with theslide surface 7, not only provide proper transmission of the tiltingmovement from plate 8 to carrier 1, but also eliminate any play from thetransmission.

It is apparent that since the gimbal 11 is carried directly by thecartridge 4, this cartridge together with the plate 8 and the supportingstructure therefor, as well as the specimen carrier 1 and the means fortransmitting movement of the plate to the carrier, form a single unitaryassembly capable of being removed from, and introduced into, themicroscope whenever the specimen is to be changed.

Referring now to FIGS. 3 and 4, it will be seen that the primarydistinction from the embodiment of FIGS. 1 and 2, in addition to thelocation of the adjusting plate beyond the unit which includes thecartridge 4, resides in the different adjusting means for bringing abouta change in angular attitude of plate 8 and carrier 1. In the embodimentof FIGS. 3 and 4 the adjusting plate 8, whose undersurface 7 is engagedby the upper ends of the rods 2 which are urged upwardly by the springs6, is supported for tilting movement about a tilt axis 9 which is normalto the principal axis 5 and extends through the plate 8; but in thiscase the tilt axis 9 is formed by a pair of bearings receiving coaxialprojections of the plate 8 situated in and carried by a gear ring 20.The adjusting means of this embodiment includes a rotary shaft 21 fixedto a pinion 22 which meshes with the gear ring 20 so that, in responseto manual rotation of the shaft 21 by means of any suitable knob or thelike fixed thereto, the gear ring 20 will turn about the principal axiswhich passes through the center of the ring 20, and thus the angularposition of the axis 9 with respect to the principal axis can also beadjusted.

With this embodiment, therefore, the angular position of the adjustingplate 8 relative to the principal axis 5 can be adjusted. However,during this rotary movement of the plate 8 about the axis 5 thecartridge 4 and the motion transmitting rods 2 maintain their positionswith respect to the principal axis 5. That is, the parts 2 and 4 do notturn about the principal axis 5 when the plate 8 turns about this axis,and of course at this time the surface 7 slides along the upper ends ofthe rods 2. In this Way it is possible, without turning the specimenitself, to provide not only a desired angle of tilt for the specimen butalso to provide an apparent rotation of the specimen in azimuth.

To adjust the tilt angle of plate 8 the adjusting means includes asecond gear ring 23 coaxially surrounding the ring 20. The gear ring 23is provided at its exterior surface with a plurality of projections 24which are received in an annular groove 25 formed in any suitable partof the electron microscope such as the vacuum housing thereof. In thisway the gear ring 23 is supported for free rotary movement about theprincipal axis 5. In the same way the inner gear ring 20 may be providedwith unillustrated outer projections received in an annular grooveformed in the inner surface of the gear ring 23 and situated at the sameelevation as the groove 25, so that the gear ring 23 directly supportsthe gear ring 20 for rotary movement about the principal axis.

For turning the ring 23 the adjusting means includes a second driveshaft 26 which is hollow and through which the inner drive shaft 21coaxially extends. The tubular drive shaft 26 is coaxially fixed with asecond pinion 27 through which the shaft 21 also extends, the pinion 27being in the form of a ring which coaxially surrounds the shaft 21. Thepinion 27 meshes with the teeth at the underside of the gear ring 23- sothat in response to rotary movement of the hollow drive shaft 26 theangular position of the gear ring 23 can be adjusted.

A cam means cooperates with the plate 8 and the ring 23 for adjustingthe angular position of the plate 8 with respect to the tilt axis 9. Inthe illustrated example this cam means includes a cam 28 extending alonga circle about the principal axis 5 and having an undersurface extendingapproximately along a spiral whose axis coincides with the axis 5. Theundersurface of cam 28 is engaged by the upper end of a cam followerprojection 29 fixed to, and projecting upwardly from, the plate 8 andsituated along an axis perpendicular to the axis 9. Hence, the change inelevation of the cam follower 29 resulting from rotation of the ring 23will result in a change in the angle of plate 8 with respect to the tiltaxis 9, and the transmission means 2 will reproduce the same angle inthe specimen carrier 1.

A leaf spring 30 is fixed to the inner surface of the ring 20 and has afree end carrying a pressure-transmitting structure which engages theplate 8 at a part thereof diametrically opposed to the cam follower 29so that with this structure the spring 30 serves to maintain the camfollower 29 in engagement with the lower camming surface of the cam 28.Thus, the rotary movement of the cam 28 together with the ring 23 willresult in movement of the plate 8 about the axis 9 more or less inopposition to the force of the spring 30, so that a definite angle oftilt of the plate 8 will be achieved, and this angle will be transmittedto the specimen carrier 1.

With this embodiment it is only required to rotate the gears 20 and 23as a unit in order to turn the plate 8 about the axis 5 without changingthe tilting angle of the plate 8 with respect to the tilt axis 9. Forthis purpose an additional unillustrated releasable coupling can beprovided for coupling the shafts 21 and 26 to each other for jointrotation.

The arrangement of the inner ring gear 20- directly within andsurrounded by the outer gear 23-, and arrangement of the inner driveshaft 21 within the outer drive shaft 26, result in an extremely compactassembly requiring the smallest possible amount of space, and thereforean extremely simple seal sutfices for passage of the shafts 21 and 26 tothe exterior of the vacuum housing of the particle beam apparatus.

The adjusting bars 14 and 15 of FIGS. 1 and 2, which are required onlyto move longitudinally, may also be guided through simple seals capableof maintaining the desired vacuum in the interior of the vacuum housing,although the outer ends of the adjusting bars 14 and 15 are accessibleoutside of the device.

The structure described above is capable of being used in an electronmicroscope, for example one of the type illustrated in FIG. 5. Referringto FIG. 5 there are illustrated proceeding from top to bottom in thedirection of the electron beam principal axis, the following componentsof the electron microscope: the cathode 43, the Wehnelt cylinder 44, theanode 45, the coil 47 of the upper condenser which has the lens gap 46,the coil 48 of the second condenser, which is not illustrated in detail,and-in the region of the lower sectionally illustrated structure of FIG.5the coil 42 of the objective lens, which has the lens gap 41. Theobjective assembly includes the upper objective pole piece 52 and thelower objective pole piece 53. The tilting assembly 49 of the inventionis shown at the lower sectional portion of FIG. 5 as a simple rectanglemounted on the specimen stage or table 51 constructed as shown in FIG.6. For simplicity, the structures for adjusting the specimen stage andfor actuating the tilting assembly 49 are not illustrated in FIG. 5. Thespecimen carrier 50 is indicated in FIG. 5 directly beneath theadjusting structure 49, and these parts 49 and 50 may correspond toeither the details of FIGS. 1 and 2 or to the details of FIGS. 3 and 4.As is apparent from FIG. 5, the specimen carrier 50 is situated at alocation where at least the upper pole piece 52 of the objective lenssurrounds the carrier, so that from FIG. 5 the difficulties encounteredwith respect to space restrictions in the immediate vicinity of thespecimen carrier are clearly apparent.

In FIG. 6 the specimen stage 60, which corresponds to the stage 51 ofFIG. 5, carries the unit 61 which includes the specimen cartridge, thespecimen carrier therebeneath, and at least the transmission means fortransmitting the tilting movement of the plate 8 to the carrier. Thisspecimen stage 60 is adjustable in a pair of mutually perpendiculardirections, as indicated by the double-headed arrows of FIG. 6. For thispurpose the stage 60 is supported for slidable movement on the uppersurface of the upper ob ective pole piece formed by the horizontal plate62. A pair of rotary adjusting knobs 63 and 64 are accessible to theoperator at the exterior of the device, and through suitabletransmissions, which include the rotary shaft 65 and 66, the rotation ofthe knobs 63 and 64 is transmitted to the turnable adjusting members 67and 68 which act on the specimen stage 60 through rods 69 and 70respectrvely. The stage 60 is provided at its periphery with rollersprotruding beyond the periphery to engage suitable surfaces which guidethe stage 60 for movement in the directlons of the double headed arrowsof FIG. 6.. The guide rollers engage stationary guide surfaces of themicroscope in the interior thereof, although the left guide rollers ofFIG. 6 engage a guide surface of a shiftable member 71 directly actedupon by a push rod 69. In this way frictional resistance to shifting ofthe stage 60 in its own plane normal to the principal axis is greatlyreduced.

The invention is not limited to the particular details described aboveand shown in the drawings. Of course the particular adjusting drivesshown in FIGS. 3 and 4 may be used with the structure of FIGS. 1 and 2so as to actuate an assembly where the adjusting plate itself forms aun1t with the specimen cartridge. On the other hand, the grmbal mountingof FIGS. 1 and 2 need not form a unit with the cartridge but instead canbe placed beyond this un1t to provide a suitable adjustment of thespecimen carner.

Furthermore, it is possible to arrange the adjusting plate together withthe adjusting structure therefor outs1de of the evacuated space, and totransmit the movement of the adjusting plate through suitabletransmission members to the three transmission members 2, independentlyof the shifting of the specimen stage as shown in FIG. 6.

Furthermore, the specimen carrier and the adjusting plate may be spacedfrom each other, not along the princ1pal axis, but, for example, in adirection perpendicular to the principal axis. This is of advantage forsome diffraction-type equipment. Moreover, several adjusting plates andtransmissions similar to the rods 2 can be arranged in series one abovethe other so that the assembly in the region of the specimen carrier isquite narrow while at other regions, for providing sufficientinterengagement between the elements, a broader spread of the drivingstructure can be provided without difiiculty.

The invention affords the advantage of producing for a specimen in aparticle beam apparatus practically any angular attitude, while at thesame time the orientation of the specimen along the principal axisremains unchanged so that the sharpness of the image is not affected bychanges in angular setting. It may be desirable to provide for thetilting structure a means for adjusting only once the elevation of thespecimen carrier so that, when the position of the specimen carrieralong the principal axis is set to provide the sharpest possible image,a further adjustment will not be required.

I claim:

1. A specimen tilting device for electron microscopes and other particlebeam apparatus, comprising a specimen carrier tiltable relative to theprincipal axis of the device, a control structure spaced from saidcarrier and tiltable about a tilt axis perpendicular to said principalaxis and situated adjacent to said control structure, actuating meansconnected with said structure for chang ing its angular positionrelative to said principal axis, and guide means extending parallel tosaid principal axis and linking said structure to said carrier fortransmitting the angular position of said structure to said specimencarrier while said guide means remains parallel to said principal axis.

2. A specimen tilting device for electron microscopes and other particlebeam apparatus, comprising a specimen carrier tiltable relative to thebeam axis of the device, a control plate spaced from said carrier in thedirection of said beam axis and tiltable about an axis perpendicular tosaid beam axis and situated adjacent said control plate, actuating meansconnected with said control plate for changing its angular positionrelative to said beam axis, and guide means extending parallel to saidbeam axis and linking said plate to said carrier for transmitting theangular position of said plate to said specimen carrier while said guidemeans remains parallel to said beam axis.

3. In particle beam apparatus, such as an electron microscope, atiltable specimen carrier, an adjusting plate spaced from said carrier,support means supporting said adjusting plate for tilting movement abouta tilt axis adjacent said adjusting plate and perpendicular to theprincipal axis of the particle beam apparatus, means for tilting saidadjusting plate about said tilt axis, and transmission means movableparallel to said principal axis and extending between and mechanicallyengaging said adjusting plate and specimen carrier for transmittingtilting of said adjusting plate to said specimen carrier.

4. In particle beam apparatus, such as an electron microscope, atiltable specimen carrier through which the principal beam axis extends,an adjusting plate having a central opening through which said principalaxis extends and situated along the latter axis at a location spacedfrom said carrier, support means supporting said plate for tiltingmovement about a tilt axis normal to said principal axis and situatedadjacent said adjusting plate, means for tilting said adjusting plateabout said tilt axis, and transmission means movable parallel to saidbeam axis and extending between and mechnically engaging said plate andcarrier for transmitting tilting of said plate about said tilt axis tosaid carrier and for situating said carrier at an angular positioncorresponding to that of said plate with respect to said tilt axis.

5. In apparatus as recited in claim 4, said transmission means includinga plurality of elongated transmission members distributed about andextending parallel to said principal axis, and means guiding saidtransmission members for longitudinal movement.

6. In particle beam apparatus, tiltable specimen carrier means adaptedto be introduced into the apparatus at least in part by movement of saidcarrier means in a given direction along the principal axis of theparticle beam, an adjusting plate situated along said principal axisbehind said carrier means relative to said given direction, supportmeans supporting said adjusting plate for tilting movement about a tiltaxis normal to said principal axis and situated adjacent said adjustingplate, means for tilting said adjusting plate about said tilt axis, andtransmission means moveable parallel to said principal axis andextending between and mechanically engaging said adjusting plate andspecimen carrier for tilting the latter, in response to tilting of saidadjusting plate, to angular attitudes corresponding to that of saidadjusting plate.

7. In particle beam apparatus, such as an electron microscope, atiltable specimen carrier, an adjusting plate, and a specimen cartridgesituated between said plate and carrier, and adapted to be mounted in aspecimen stage, said cartridge, carrier, and plate all being arrangedalong a principal axis along which the electron beam travels, supportmeans supporting said adjusting plate for tilting movement about a tiltaxis normal to said principal axis and situated adjacent said adjustingplate, means for tilting said adjusting plate about said tilt axis, andtransmission means moveable parallel to said principal axis andmechanically engaging said adjusting plate and carrier for transmittingtilting of said plate to said carrier and for situating said carrier atan attitude corresponding to that of said plate, said cartridge beingformed with openings through which said transmission means extends.

8. In apparatus as recited in claim 7, said transmission means includingelongated transmission members extending parallel to and distributedabout said principal axis, said cartridge being formed with saidopenings to accommodate said elongated transmission members whichrespectively extend through said openings of said cartridge, and saidcartridge guiding, at said openings thereof, said elongated transmissionmembers for longitudinal movement parallel to said principal axis.

9. In apparatus as recited in claim 8, spring means mechanicallyconnected to said transmission members for urging the latter toward saidadjusting plate, and said transmission members respectively having freeends slidably engaging a surface of said plate and maintained inengagement with said surface by said spring means.

10. In apparatus as recited in claim 7, said support means including agimbal on which said plate is mounted for tilting movement about saidtilt axis.

11. In apparatus as recited in claim 10, said cartridge supporting saidgimbal for tilting movement about a. second axi normal to said principalaxis and perpendicular to said tilt axis.

12. In apparatus as recited in claim 11, said transmission meanscarrying said object carrier as Well as transmitting thereto movement ofsaid adjusting plate; and said cartridge, adjusting plate, objectcarrier, transmission means, and support means all forming a unitaryassembly.

13. In apparatus as recited in claim 7, said transmission mean carryingsaid object carrier and forming with the latter and said cartridge asingle unitary assembly, said support means and plate being situatedbeyond said assembly.

14. In apparatus as recited in claim 7, a specimen stage carrying saidcartridge, and adjusting means mechanically connected to said stage forshifting the latter in a plane normal to said principal axis, said meansfor tilting said plate about said tilt axis maintaining the adjustmentof said plate during shifting of said stage.

15. In a particle beam apparatus, a tiltable specimen carrier, aspecimen cartridge, and an adjusting plate all situated along theprincipal axis of the particle beam apparatus, said cartridge beinglocated between said plate and said carrier, support means supportingsaid plate for tilting movement about a tilt axis normal to saidprincipal axis and situated adjacent said plate, transmission meansmoveable parallel to said principal axis and supported by said cartridgeand mechanically engaging said plate and carrier for tilting the latterin the same way that said plate is tilted, and adjusting meansmechanically connected with said plate for adjusting the angularposition thereof with respect to said tilt axis.

16. In apparatus as recited in claim 15, said support means including agimbal surrounding said plate and supporting the latter for tiltingmovement about said tilt axis, and said gimbal itself being supportedfor tilting movement about a second axis normal to said tilt axis andprincipal axis, said plate having a projection situated along saidsecond axis and said gimbal having a projection situated along said tiltaxis, and said adjusting means including a pair of elongated adjustingmembers respectively parallel to said tilt and second axes and movablein the directions in which said tilt and second axes extend, saidadjusting members respectively having inclined wedge surfaces engagingsaid projections so that the longitudinal positions of said adjustingmembers will determine the angular positions of said plate and gimbalrespectively, to determine the angular attitude of said plate whichthrough said transmission means determines the angular attitude of saidspecimen carrier.

17. In apparatus as recited in claim 15, said support means including arotary gear ring surrounding and turnable about said principal axis andhaving its center situated in said principalaxis, said gear'ringsurrounding and carrying said plate while supporting the latter fortilting movement about said tilt axis, and said adjusting meansincluding a drive mechanically connected to said gear ring fordetermining the angular position thereof with respect to said principalaxis so as to determine the angular position of said tilt axis withrespect to said principal axis.

18. In apparatus as recited in claim 17, a second gear ring coaxial withsaid first-mentioned gear r ng, said adjusting means including a seconddrive mechanically connected to said second gear ring for determiningthe angular position of the latter with respect to said principal axis,and cam means mechanically connected to said plate and second gear ringfor tilting said plate about said tilt axis in response to movement ofone of said gear rings about said principal axis with respect to theother of said gear rings.

19. In apparatus as recited in claim 18, said cam means including a camcarried by said second ring and a cam follower carrier by said plate andengaging said cam.

20. In apparatus as recited in claim 18, said drives for said pair ofgear rings respectively including a pair of pinions having a common axisand meshing respectively with said gear ring's, said drives including,in addition to said pinions, an inner rotary shaft coaxially fixed toone of said pinions and extending through the other of said pinions, andan outer hollow tubular drive shaft through which said inner shaftextends, said hollow drive shaft being coaxially fixed to the other ofsaid pinions.

References Cited UNITED STATES PATENTS 3,230,365 1/1966 Nagahama250-49.5 3,240,934- 3/1966 Watanabe et a1 25049.5

WILLIAM F. LINDQUIST, Primary Examiner.

U.S. Cl. X.R.

